The Study of Instinct Unraveling the neurobiological basis of behavior
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The Study of Instinct
Unraveling the neurobiological
basis of behavior
Outline
• Part I: basic concepts in the study of the biological basis of behavior
• Part II: modern tools for studying behavior
• Part III: recent discoveries in the neurobiology of behavior;
implications for human health.
Motivation
Outline
• Part I: Basic concepts in the study of the biological basis of behavior
• Part II: modern tools for studying behavior
• Part III: recent discoveries in the neurobiology of behavior and
implications for human health
Behavior
the total movements made by an
intact animal.
Basic concepts of behavior
External and internal stimuli
• external = things in our
surrounding environment
• internal = our “drives” and
motivations (e.g. hunger, thirst)
Innate or instinctive behaviors
those that are not changed through
learning.
Ethological approach
• Pros: observe whole animal
in natural environment.
• Cons: subjective; lacks
mechanistic insight.
Neurophysiological approach
• Pros: controlled experiments;
rigorous and quantitative
• Cons: Constrained, non-
naturalistic conditions.
Two historical approaches to studying behavior
The four Fs of evolution
• Fighting
• And…
• Fleeing
• Feeding
Drive, homeostasis, and valence
• Homeostasis: The regulation of biological
systems such that internal conditions remain
stable, at some predetermined “set point.”
• Hunger, thirst, mating, sleep, thermoregulation,
etc. are universal motivational drives.
• Things that bring us closer to our set point take
on a positive valence (good/pleasurable)
• Things that move us away from our set points
take on a negative valence (bad/unpleasant)
Homeostasis, drive, and valence
• Hypothalamic neurons controlling basic drives integrate information from the brain and body.
The hypothalamus contains circuits
controlling our basic drives
• Achieve this by sending neural signals to multiple brain regions in parallel.
• Drive circuits coordinate the brain and body in order to produce adaptive behaviors.
external stimuli
internal stimuli
Questions?
• Part I: Basic concepts in the study of the biological basis of behavior
• Part II: modern approaches to the study of behavior
• Part III: recent discoveries in the neurobiology of behavior and
implications for human health
Outline
• Part I: Basic concepts in the study of the biological basis of behavior
• Part II: modern tools for studying of behavior
• Part III: recent discoveries in the neurobiology of behavior
“Turn to Right”
Unbiased methods for observing behavior
Data courtesy of Alex Wiltschko, PhD
Unbiased methods for observing behavior
Objective classification of behaviors
Rear and
Turn
Run, Forrest,
Run
Sway
Walk
Pause
Unbiased methods for observing behavior
Hunch
And Freeze
Hunting
Dog
Data courtesy of Alex Wiltschko, PhD
Measuring neural activity: calcium imaging
Measuring neural activity: calcium imaging
Controlling neural activity: optogenetics
Genetically engineered
animal + fiber optic
Questions?
• Part I: Basic concepts in the study of the biological basis of behavior
• Part II: modern approaches to the study of behavior
• Part III: recent discoveries in the neurobiology of behavior and
implications for human health
Outline
• Part I: Basic concepts in the study of the biological basis of behavior
• Part II: modern approaches to the study of behavior
• Part III: recent discoveries in the neurobiology of behavior
Optogenetic control of “hunger neurons”
Genetically engineered
animal + fiber optic
Laser OFF Laser ON Laser OFF
30 min. 30 min. 30 min.
0.0
0.2
0.4
0.6
0.8
Foo
d c
onsum
ption
(g
ram
s)
“Hunger neurons” carry a negative valence
Optogenetic control of “aggression neurons”
Video courtesy of Dr. Dayu Lin (NYU)
Conclusions
• The hypothalamus is a key brain region
controlling the basic motivational drives
common to all animals.
• New technologies allow neuroscientists to
rigorously observe behavior, record neural
activity, and manipulate neurons in awake,
behaving animals.
• Techniques such as optogenetics allow us
to attribute causality to specific brain
circuits in the control of motivational drives
Clinical applications… and beyond?
• Therapy – variable effectiveness; doesn’t work for
certain problems, e.g. epilepsy, neurodegeneration
• Drugs – Variable effectiveness, commonly have
multiple side effects
• Surgery – Highly invasive; irreversible.
Clinical applications… and beyond?
• …in principle, could also control more
“psychological” traits e.g. depression,
aggression.
• Optogenetic therapies?
• Recently used to control pain in mice;
opiates are common treatment in
humans
• Reversibly “turn off” parts of the
brain, e.g. intractable epilepsy
Credit: Image Source: Jose Grajales-Reyes (Gereau Lab)
Acknowledgements
• Co-directors: Steph Guerra, Katie Wu ([email protected])
• Seminar series directors: Jordan Wilkerson, Stephen Portillo
• Graphics artist: Olivia Foster
www.sitn.hms.harvard.edu
Questions?
www.sitn.hms.harvard.edu
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